Tuesday, 28 October 2014

On the rare occasions when I visit the coast from
land-locked Hertfordshire, I like to go out mackerel fishing, in company with
other holidaymakers. Boat owners run these trips alongside those for
sightseeing, and the necessary tackle is provided. Local knowledge of where shoals
of fish are likely to be found is invaluable and, after chugging out to a
suitable location, the boat’s engine is turned off and instruction given on how
to lower the weighted line to the sea bed, raise it a little, let it drop,
raise it again, etc. No bait is used, but hooks (at least three) are held out
on traces that have brightly coloured feathers attached. In no time, the tug of
fish is felt and the line is reeled in, sometimes with a mackerel on each hook,
and everyone seems to have success. Occasionally, other fish are caught, but it
is mackerel that make up almost all the catch and, on good days, they begin to
pile up in trays, or buckets, on deck.

For many people on the trip, catching mackerel is pleasure
enough but, for others, the freshly-caught fish make a splendid supper. Whereas
meat, and especially game, improves with hanging, fish are best eaten as fresh
as possible. There are a number of ways in which mackerel can be enjoyed and
they are both delicious and good for one’s health. The simplest approach is to
barbecue, or they might be eaten as a ceviche of raw fish, and they can also be
smoked to allow preservation for several days, or even weeks. [1] My own
favourite recipe comes from childhood when we were given freshly-caught
mackerel by Mr Revell, who lived along our road and always seemed to have an
excess when he went fishing from the end of Paignton Pier. We had them soused
in vinegar, [2] with bay leaves placed into slashes in the flesh, and I can
remember the taste well.

Everyone catching Atlantic mackerel (Scomber scombrus), whether to eat or not, is impressed by the
appearance and muscularity of the fish. The muscles used for swimming are
arranged in blocks and run along the body, from just behind the head to the
tail, and they drive the caudal fins (tail). If we looked closely, we would see
that three types of muscle are present. Running along the sides of the fish are
red muscles, while ca. 90% of the bulk of the flesh consists of white muscles,
or intermediate pink muscles. [3] Red muscles are very different in structure
and function to the other types. They are well supplied with oxygen and do not
tire easily and this contrasts with the white muscles, which show the opposite
qualities, with the pink muscles (lying within the white muscle mass) having a
slightly longer endurance. Red muscles are thus used in cruising, while the white
and pink muscles are used for bursts of acceleration, such as are needed when
avoiding prey or in predation.

In addition to powering the caudal fins, the muscles also
provide the outline of the fish. Mackerel have an “idealised streamlined shape”;
one where the widest part of the body is about one third from the front and
where the length is about four times the width. This shape is shown in the
diagram below and one needs to visualise it in 3-D. The mackerel makes a good fit and, to understand why this is advantageous, we need to imagine
that water is arranged into sheets and that turbulence results when these sheets
are disrupted. At some point along the body, the sheets of water passing over
the mackerel peel away from close contact with the surface and this is referred
to as the separation point (SP, see arrows in the diagram below). Beyond the SP, the sheets of water
stop flowing smoothly and this results in drag, but the streamlined shape means
that the water layers hold to the body for longer, resulting in a smaller
turbulent wake behind the fish. Its shape thus results in less drag, so less
power is then needed by the fish in both slow, and fast, swimming

Scales that are sunk into the skin cause micro-turbulence in the water
flowing just over the surface of the fish and this provides a “lubricant” over which
the fast-moving sheets just a little further away from the body can slide, further
diminishing the risk of separation. Of course, this is only one function of the
scales, as they also serve for protection. More obvious features of the
surface are the fins and these are rigid and can be held out into the smooth
flow of water passing over the fish when they are needed most during rapid swimming. They function like the flights of arrows,
or darts, in counteracting pitch, roll and yaw and, like the body profile and
the musculature, are elegant designs.

However, mackerel did not have a designer and all the structures
that we see evolved over time. So, too, did other features of these fish, such
as their good eyesight (that enabled them to spot the feathers on my fishing
line); the swim bladder (an extension of the gut) that allows them to float
without expending energy; their efficient means of acquiring oxygen through the
gills; and many other modifications, including their extraordinary musculature
(which is so good to eat). All evolved and we can only speculate how: were
there dramatic mutations, or more gradual changes in anatomy, morphology and
physiology? Sometimes, belief in a Creator seems like an easier way to get
answers.

Friday, 17 October 2014

Unlike the majority of scientific finds, descriptions of new dinosaurs are often reported widely by the World’s media, as they grip the
imagination of readers and viewers. A recent example is the discovery of Dreadnoughtus schrani in Argentina,
where about 45% of the skeleton was found. [1, 2] Individual bones were cleaned
carefully and these allowed the reconstruction shown in the illustration below,
with the bones recovered shown in white. The skeleton was then completed using
assumptions based on a scholarly prediction of the size, and shape, of the
missing parts. Dr Lacovara of Drexel University and his colleagues were
delighted to have both a femur and a humerus, as measurements taken from these two
bones allow a reasonably accurate estimate of the mass of the living Dreadnoughtusto be made - at nearly 60,000 kg, [3]
equivalent to more than 10 African elephants. [2]

Both a BBC article, [1] and the one by Drexel University,
[2] use the same artist’s impression of a living Dreadnoughtus, although the BBC piece blanks out the background, something
that gives context and scale, as does comparison with the size of contemporary
humans (see the illustration above). But
how accurate is the image of the reconstructed dinosaur to the living form?
Fortunately, there are sufficient bones from this specimen to assess the
insertion of muscles and thus the outline of some parts of the animal, based on
very close examination of bone surfaces by experts. [3] However, while almost
all the tail bones were recovered, there is little of the neck and even less of
the head, so what is the basis for their appearance in the artist's impression?

There is a problem in making reconstructions of whole
animals from skeletal fragments and I’m sure that many dinosaurs are painted
with far less evidence of structure than is available for Dreadnoughtus. However, it is the illustrations that grab the
attention, although the size of mounted skeletons, or casts, in museums
certainly give a sense of the huge size of some of these reptiles. Dinosaurs
have been afforded another level of presentational skill in being used in animatronics
and computer simulations [4,5] that often feature colour, sounds and even
behaviour and may be based on a little too much imagination. Nevertheless,
these images are widely held to be accurate by enthusiastic onlookers.

Our fascination with dinosaurs goes back to the
time of the popularisation of fossil hunting and of Natural History in the
Nineteenth Century. Among the more famous exhibits of that time are the
life-size models of dinosaurs commissioned for the move of the Great Exhibition
to the newly-constructed Crystal Palace in 1854. These models remain in the
grounds of the demolished Palace (see below) and are still visited by families,
whose children delight in their scary nature, despite their obvious lack of
life.

In the Nineteenth Century, we knew that dinosaurs existed
millions of years before the present and this widely accepted interpretation
provided a challenge to those who believed in the literal account of Creation
in The Bible. Faced with this
conflict, Philip Henry Gosse, wrote Omphalos,
[6] in which he advanced a theory that suggested that fossils of such age did
not compromise the belief that everything was created over six days, just a few
thousand years ago. In the first section of his book, Gosse describes several
fossil discoveries accurately and accepts that they were present during
different geological time periods, as advanced by Lyell, amongst others. The
text is illustrated by artist’s impressions of the living animals in their
natural habitats, several in the form of signed woodcuts by Gosse himself and
two of these are shown below.

As a brilliant Natural Historian, Gosse was fascinated by
the biology of these creatures:

..the most characteristic animals
[of the Lias] were great marine Reptiles, of strange and uncouth forms, to
which the present world presents us no known analogy. One of these was the Icthyosaurus, which closely resembled a porpoise
in form, but thirty or forty feet in length, with a vertical fish-like tail,
and two pairs of paddles; a mouth set with stout crocodilian teeth, and
enormous eyes. Another form was that of the Plesiosaurus,
scarcely less in size than its fellow, which in the outline of its body it
resembled: it was distinguished, however, by an extraordinary length of neck,
slender and swan-like.. [6]

However, his theory concluded that they had only had the
appearance of being alive as everything was created by God at that huge event a
few thousand years ago and this included the Earth’s strata and the fossils
that they contain. It is, of course, a rather silly theory produced by someone with
complete faith in the words of The Bible,
yet accepting the logic of geological time. There was no doubting his enthusiasm
for dinosaurs, however, even if he believed that they had never existed.
Interestingly, in the context of the quote given above,
Gosse put forward his view that sightings of “sea serpents” may be explained by
the continued existence of reptiles like ichthyosaurs and plesiosaurs. [7]

What is it about dinosaurs that make them more fascinating to
us than other fossil animals? In part, it relates to their size, although many
small dinosaurs do not have the glamour, and almost mythological status, of
larger forms. It is also because we really want to see living forms, rather
than impressions of various kinds. Some hope that, like the sea serpents
sighted in the Nineteenth Century, aquatic dinosaurs continue to exist, even
though the chances are miniscule. In the United Kingdom, we are familiar with
the “monster” that is believed to inhabit Loch Ness, but studies using sonar,
and other techniques, have, predictably, drawn a blank. Wouldn’t it be fun if
we did find a living dinosaur, though?

Monday, 6 October 2014

Walking at a good pace is regarded as an excellent way of
keeping fit, both physically and mentally. Some prefer to use treadmills in a
gymnasium, others to be part of a social exercising group, and yet others prefer to take solitary walks in Nature. My enjoyment of walking started when I was growing up in Devonshire and went with my
family into the countryside (I’m the little chap, aged 3, leading in the picture below). I preferred
my own company on walks in my teenage years, but also hiked with friends on many
occasions and enjoyed our conversations. I had no idea of the physical and
mental benefits; I just enjoyed walking through lanes, over Dartmoor, or at
the coast - including jumping from rock to rock around headlands, something that carried
the risk of falling, or of being cut off from the tide. Other walks held little
danger, although barking sheepdogs, and dogs other breeds, running from farms,
or other properties, could be off-putting. Aside from that, it was all about
the enjoyment of striding out, looking at Nature,
feeling the warmth (or cold) and generally becoming lost in the experience.
It’s still the way I feel when taking country walks, and I still prefer to go
alone.

Although I’ve rarely sought explanations for the enjoyment of solitary
walks, others have. For example, Rousseau writes of his introspection:

The habit of searching into
myself caused me, at length, to lose the feeling, and almost the remembrance,
of my misfortunes. I thus learnt, by my own experience, that the source of true
happiness is within us, and that it does not depend on man to render truly
miserable him who knows how to determine to be happy. These four or five years
I have constantly tasted those internal delights which kind and gentle souls
find in contemplation. Such raptures, such exstasies, I sometimes experienced
in thus walking alone, were enjoyments I owed my persecutors; without them I
should never have felt or known the treasures I carried within me. [1]

My pleasure is not driven by persecutors and comes from a combination
of the exercise and what I see, hear and smell. Even the same route has something
different to offer through the seasons. I once asked a low handicap golfer if he
ever became bored playing the same links course every day and he replied that
it was never the same 18 holes. There were differences in the direction of the
wind and its strength; together with differences in dampness, both of the air
and of the ground, and all these factors needed to be taken into account when
making decisions about the choice of club, or of shot. The golf course was
always changing in subtle ways and country walks are never really repeats, for similar
reasons to those put forward by the golfer.

What is the scientific evidence for the benefits of country walks?
Recently, I read an interesting article in New
Yorker by Ferris Jabr, entitled “Why Walking Helps Us Think”. [2] He
writes:

What is it about walking, in
particular, that makes it so amenable to thinking and writing? The answer
begins with changes to our chemistry. When we go for a walk, the heart pumps
faster, circulating more blood and oxygen not just to the muscles but to all
the organs - including the brain. Many experiments have shown that after or
during exercise, even very mild exertion, people perform better on tests of memory
and attention.. ..Because we don’t have to devote much conscious effort to the
act of walking, our attention is free to wander - to overlay the world before
us with a parade of images from the mind’s theatre. This is precisely the kind
of mental state that studies have linked with innovative ideas and strokes of
insight.

Ferris then goes on to mention the research of Marily Oppezzo
and Daniel Schwartz of Stanford University on the link between walking and creativity
and also a study by Marc Berman and colleagues at the University of Michigan on
the importance of walking in Nature. That stimulated me to read their original
research papers.

Oppezzo and Schwartz [3] used separate experiments to allow
them to compare sitting, walking on a treadmill, and walking outside, with
subjects being assessed using psychological tests. In a thorough discussion of
all the possible explanations for their results, they found that:

Walking substantially enhanced creativity..
..[and] is an easy-to-implement strategy to increase appropriate novel idea generation.
When there is a premium on generating new ideas in the workday, it should be
beneficial to incorporate walks..

..Walking outdoors on a busy
campus did not significantly increase appropriate novelty compared with walking
indoors, although the more varied stimulation did appear to increase novelty.
This suggests that walking may be effective in many locations that do not have
acute distractions. The social context also needs investigation. Participants
were encouraged to talk aloud to a friendly researcher. Will the effects
generalize to solitary walks?

A good question. It was the effect of walking outdoors that
was investigated by Berman et al.. [4] They used two experiments, in the first
of which subjects were compared after walking in the city of Ann Arbor and
after walking in the relative tranquillity of Ann Arbor Arboretum. There was an
improvement in directed-attention ability in the subjects that had walked in
the arboretum. Interestingly, a second experiment that showed subjects pictures of nature compared to urban areas in a quiet room produced similar
results on cognitive functioning.

Walking in a natural environment is thus shown to be
positive, supporting a commonly-held view, and certainly one which I now
realise conditioned my love of country walks. It is interesting that Oppezzo
and Schwartz allude to solitary walking as this is certainly my preference as
it is/was for others. Ferris Jabr comments that Wordsworth:

..walked as many as a hundred and
eighty thousand miles in his lifetime, which comes to an average of six and a
half miles a day starting from age five. [2]

Such prodigious amounts of walking through the countryside (perhaps
there is a little exaggeration here?), led to creativity, but also to deeper
thoughts. As Wordsworth wrote [5]:

..this prayer I make,

Knowing that Nature never did
betray

The heart that loved her; ‘tis
her privilege,

Through all the years of this our
life, to lead

From joy to joy: for she can so
inform

The mind that is within us, so
impress

With quietness and beauty, and so
feed

With lofty thoughts, that neither
evil tongues,

Rash judgements, nor the sneers
of selfish men,

Nor greetings where no kindness
is, nor all

The dreary intercourse of daily
life,

Shall e’er prevail against us, or
disturb

Our cheerful faith that all which
we behold

Is full of blessings..

I suppose that is what solitary walks in the countryside are
really all about - an immediate pleasure from exercise in such surroundings, the enhancement of creativity, and adding to a store of deep thoughts. They also bring respect for plants,
animals and landscape that reminds us that we, too, are
part of the natural World. So much of our time is spent in such an unnatural
one and walking in the countryside takes us back to the environment in which
we evolved, and which we are trying to destroy in many ways. Is that too
fanciful an idea? Perhaps I should attempt to answer that question after taking
a few long walks and then report back in a future blog post?

In conclusion, I’ll give another quote from Berman et al.
[4]:

Imagine a therapy that had no
known side effects, was readily available, and could improve your cognitive
functioning at zero cost. Such a therapy has been known to philosophers,
writers and laypeople alike: interacting with nature.

[1] Jean-Jacques Rousseau (1783) The Reveries of the Solitary Walker (translated from the French).
London, J.Bew.